Heated seat element fixing question

["Doyt W. Echelberger" <Doyt@nwonline.net>]

I have 2 Q's and want the heated front seats working by next winter.
Replacement elements cost $127 each and we are talking 4 elements. So I
tried to fix the old ones using archive info from the past few years.

Armed with BTDT and Bentley's, I pulled the front seats out of two the cars
and stripped them down to the heater elements, found the wire breaks,
stripped the wire ends, twisted them in a fisherman knot, acid fluxed the
joint and soldered it with fine solid core electrical solder, and covered
it with a shrink tube. Then I tested each circuit for continuity at the
connectors. All showed conductivity.

Now when I run the seat heaters back in the cars, the repair points get so
hot you could burn a finger touching them through the leather.  This
doesn't seem good to me.

Anybody know how to get rid of those hot spots?  Should I solder the wire
ends to opposite sides of a penny to spread out the heated surface for
better heat distribution? Is the shrink wrap the problem, trapping heat and
allowing build up to a hot spot? Why is the heat building up there in the
first place? Is it a property of the solder joint, or a property of the
shrink tube insulation, or both?  Data point: The shrink tube looks to be
much thicker and maybe a different material than the original covering of
the resistance wire. I suspect it.

The practical question is, how can I avoid producing a hot spot when I fix
the break point? maybe somebody has already solved this problem.

An interesting theoretical point is, how do the electrical failures get
started and develop in the first place. But I don't want to get lost in
theory.I can now pull a seat out and tear it down and put it back together
pretty fast, but that doesn't help with the hot spots, and I'm afraid I
won't have heated seats very long this winter unless I change something in
those repairs.

Doyt Echelberger

87 5kcstq (seat heater elements easy to find and see break points)

86 4kq  (very different looking seat heater elements than the 5k. Almost
impossible to do pin-out to find breaks)